小技巧，写一个自定义的deepcopy函数,速度比原装的快。

In [4]: a = [1,2,3]                                                                         

In [5]: from pickle import loads,dumps                                                      

In [6]: my_deepcopy = lambda x : loads(dumps(x))                                            

In [7]: timeit -n 1000 -r 3 my_deepcopy(a)                                                  
982 ns ± 40.5 ns per loop (mean ± std. dev. of 3 runs, 1000 loops each)

In [9]: from copy import deepcopy                                                           

In [10]: timeit -n 1000 -r 3 deepcopy(a)                                                    
3.21 µs ± 177 ns per loop (mean ± std. dev. of 3 runs, 1000 loops each)

从上面的代码运行来看，时间快了三分之一，但都是单位尽然到了纳秒级别，是不是我电脑太快了。